The present invention relates to an absorption refrigerating system for use with refrigerant and inert auxiliary gas. Absorption refrigerating systems of this type conventionally use ammonia as the refrigerant, water as the absorbent, and hydrogen as the auxiliary gas, although other substances or combinations thereof may be used in some systems.
The functioning of a system of this type is well known to those skilled in the art. Basically, the system functions as follows: through the application of heat energy to a generator, pure refrigerant vapor is produced, condensed in a condenser and fed to an evaporator, where it evaporates at a low temperature into an atmosphere of auxiliary gas, weak in refrigerant vapor.
To maintain evaporation at a constant low temperature, a steady supply to the evaporator of fresh weak gas is necessary. This is achieved through a circulation of gas between the evaporator, where it is enriched, and the absorber where it is regenerated through absorption of refrigerant vapor into an absorbent-refrigerant solution.
The amount of refrigeration generated depends on the amount of refrigerant evaporated in the evaporator. The temperature at which the evaporation occurs, ideally, is the saturation temperature of the weak gas. In reality, however, this temperature is higher, depending on such factors as surface loading of the evaporator and of the degree of precooling of the refrigerant and weak gas entering the evaporator.
One form of well known evaporator structure allows, in the ideal case, precooling of the incoming media down to the minimum temperature of the evaporator, and thus realizes, ideally, an evaporation temperature equal to the saturation temperature of the weak gas. This is achieved by dispensing the refrigerant and weak gas conduits in heat exchange contact with the evaporator tube through its entire length up to an initial point.
For big refrigerators, however, especially when the coldest part of the evaporator is formed as a flat coil for high ice-making capacity, this arrangement causes problems in the manufacture of a long and continuous coil containing three ducts in parallel. Further, the material cost thereof is high. Further, such a coil, when coaxial tubes are used, has a tendency to become blocked by liquid refrigerant collecting in it and, thus, raises serious operational problems.